Agglomeration of finely-divided ferruginous ores, concentrates and the like



AGGLOMERATION OF FINELY DIVIDED FERRUGINOUS ORES, CONCENTRATES, AND THE LIKE Filed Oct. 2, 1930 y 1932- A. FOLLIET ET AL 1,865,203

Patented July 5, 1932 UNIT D STATES PATENT OFFICE ALEXANDRE FOLLIIE'I. AND NICOLAS SAINDERICHIN, OI PARIS, FRANCE AGGI'OMERATION OF FINELY-DIVIDED FERRUGINOUS ORES, CONGENTBATES AND THE LIKE Application filed October 2, 1930, Serial No. 486,054, and in France October 30, 1929.

According to the present invention finelydivided ores, concentrates or other ferruginous materials are subjected to a continuous or intermittent process of agglomeration b the progressive action of air heated to a big temperature in suitable heaters and blown at a suitable pressure on a mixture of the materials to be treated with a suitable proportion of fuel, that is preferably lean 1n chario acter, to provide additional heat.

This mixture, arranged in a thin layer and fed gradually forward in a refractory chamber of suitable length and section, is sub- Lected to the energetic action of jets of air, eated to temperatures of the order of 650 to 800 C., over only a comparatively short length near the point at which the resulting porous agglomerates are discharged.

Two main cases rise in practice ((2) Iron ores and products which do not contain sulphur; and

(b) Ores or products containing a varying amount of sulphur, such for example as roasted pyrites, ores and products contain ing arsenic, zinc, lead or any other volatile im urities.

n the first case, in the absence of sulphur or sulphides, the necessary quantity of'fuel to provide the additional heat, may be added in the first place to the material employed.

In the second case, the fuel will be added in the same apparatus in onlv the last zone, after the material in a suitable state of division has been subjected to a penetrating blast of air at a high temperature, a treatment which is continued in the last zone in the presence of the incorporated fuel.

The air blast, heated to 650 to 800 C. and acting alone on the sulphur-containing material arranged in a thin layer, causes the objectionable sulphur contents and also the volatile contents such as arsenic, lead, zinc and so forth to be eliminated by roasting and at the same time effects a preliminary heating which facilitates the final agglomeration in the last zone after the addition of fuel.

The process forming the subject of the present invention may be carriedout in rotary kilns of suitable dimensions, having a refractory lining, or in movable-hearth furnaces such as certain roasting ovens, or in any other arrangement in which the material is automatically fed forward in a thin layer.

The air is blown in at a predetermined temperature and pressure, in the form of flat 55 penetrating jets acting on a restricted length of the layer at the end of the operation, by means of a cylindrical nozzle with successive apertures or by means of any other device fulfilling the same purpose.

In the case of materials containing sulphuretted elements, for example, arsenic, lead and zinc, the invention may be carried out by the device shown in the accompanying drawing, in which Figure 1 shows a the furnace, 4

Figure 2 a cros-section on the line IIII of Figure 1, and

Figure 3 a cross-section on the line IIIIII 10 of Figure 1.

In the drawing, the ore from the hopper,

C, passes progressively under jets of air at a high temperature, t from the main tuyere,

T, the roasted products then entering a cylin- 15 drical chamber of large cross section, where they receive the necessary reducing carbon from the piping and hopper, R.

The intimate mixture of the products of the roasting and reduction brought about by I0 the rotary movement, then passes under jets of air at a high temperature, t, from the same main tuyere, T. v

. The metals volatilized by this reaction, are led back along the chamber, F, together with the products of combustion, into a chamber, D, after passing through a flared pipe, E, which is stationary and traversed by the feed pipe, C, this backward lead efl'ecting a preliminary heating of the layer of material moving forward. The residuals, deprived of all the volatile metals, are automatically discharged in the form of granules into a chamber, S.

From the chamber, D, the products result- 05 ing from the reaction are drawn out and discharged for further treatment through a condensing apparatus, filters and the like, forming no part of the present invention.

Under the action of the air, which is raised 1 to longitudinal section of to a constant working temperature of 650 to 800 0., as required, the carbon is burned in a known manner and develops considerable heat, even when the air blown in is much in excess. According to the proportion of added fuel in the material treated, the mixture, on account of the heat developed, reaches a suitable sintering point near the discharge point where the final high-temperature air blast is introduced.

Having now described our invention, what we claim as new and desire to secure by Letters Patent is 1. A process for agglomerating finelydivided ferruginous material, consisting 1n feeding forward said material in a thin layer, mixing carbonaceous fuel with said material prior to said layer entering the final zone of its forward feed, subjecting said mixture to the action of penetrating jets of air heated to temperatures of the order of 650 C. to 800 C. over only a final zone adjacent the end of said forward feed, and leading hot gaseous products from said final zone subjected to said jets back along said layer to preheat same.

2. A process as claimed in claim 1, in which said carbonaceous fuel is added at a point near the end of said forward feed, the action of said penetrating jets of air being confined to the zone of mixed ferruginous material and carbonaceous fuel.

3. A process as claimed in claim 1, in which said carbonaceous fuel is added at a point near the end of said forward feed, said penetrating jets acting not only on the zone of mixed ferruginous material and carbonaceous fuel but also on a zone of said ferruginous material anterior to the point Where said fuel is added.

In testimony whereof we have signed our names to this specification.

ALEXANDRE FOLLIET. NICOLAS SAINDERICHIN. 

